U.S. Pat. No. 4,368,009 to Heimovics, et al., whose contents are incorporated herein in their entirety by this reference, illustrates an aspirator intended to inflate structures including aircraft evacuation slides and rafts. The aspirator includes a housing made of fiber-reinforced plastic material and a pair of metal flapper valve plates. High-pressure gas enters the top of the housing in a single location along the (central) longitudinal axis of the housing, essentially perpendicular to a plane containing the flapper valve plates. The gas thereafter is exhausted by jets within the housing so as to create a localized region of low pressure therein, existence of which causes the flapper valve plates to open. Opening of the plates, in turn, allows ambient air to enter the housing for inflating a slide or raft.
An existing aspirator of the assignee of this application (referred to herein as the “Existing Air Cruisers Aspirator”) comprises a housing made principally of metal, a pair of metal flapper valve plates, and two sets of jet nozzles spaced longitudinally within the housing. High-pressure gas enters the housing in two locations spaced longitudinally along a housing wall, essentially parallel to a plane containing the flapper valve plates. An inner concentric ring of nozzles positioned closer to the valve plates communicates with an upper gas entry location, while an outer concentric ring of nozzles positions farther from the valve plates communicates with the lower gas entry location.
Although the Heimovics patent details an aspirator in which high-pressure gas enters the top of the housing, most commercially successful aspirators, including the Existing Air Cruisers Aspirator, are side-entry devices. This configuration allows the entry apertures to be positioned longitudinally adjacent the nozzles, minimizing the distance the high-pressure gas must travel within the housing before exiting via the nozzles. Reducing the travel distance obviously decreases the time required for aspiration to begin; it reduces loss of gas and gas pressure as well.
Forming entry apertures in the metallic side wall of the Existing Air Cruisers Aspirator does not materially compromise the strength or integrity of the wall. Doing so in non-metallic devices may be problematic, however. Nevertheless, need for principally non-metallic aspirators is increasing as airframe manufacturers, in particular, seek to design aircraft of decreased weight. Hence valuable to these manufacturers are efficient, reliable aspirators of reduced weight.